Online advertising may be an important source of revenue for enterprises engaged in electronic commerce. A number of different kinds of page-based online advertisements are currently in use, along with various associated distribution requirements, advertising metrics, and pricing mechanisms. Processes associated with technologies such as Hypertext Markup Language (HTML) and Hypertext Transfer Protocol (HTTP) enable a page to be configured to contain a location for inclusion of an advertisement. An advertisement may be selected for display each time the page is requested, for example, by a browser or server application.
For a search engine or search website, advertisements may be associated with one or more of the search terms that are entered. A search term may also be referred to as a keyword or query. Advertisers may be given the option of purchasing an association with various search keywords for a fee. When the purchased search keywords are entered by a user, the advertiser's ads are shown on the results page for that search keyword. The fee for a search keyword may be a fixed rate or may be based on the number of times the search keyword is used, or be paid based on the number of times the advertisement is viewed or clicked on by a user. The display of advertisements may be based on targeting of the particular user or targeting based on the content of a page. If a targeted advertisement is not available based on the page content, then any randomly or otherwise selected advertisement may be shown. Accordingly, it may be helpful to target users even when advertisements are not available that target the page content.